Device including steering cables for creating a cavity or a channel in bone

ABSTRACT

A device for creating a cavity or a channel in bone. First and second steering cables are coupled to a flexible elbow or a tip of a shaft. A control assembly is operably coupled to the first and second steering cables and configured to tension one of the steering cables and slacken another one of the steering cables so as to flex the flexible elbow. The control assembly may include a steering block axially movable within a handle with a knob threadably coupled to the steering block. The steering block may be rotatably fixed within the handle. The first and second steering cables may be anchored to the steering block, such as to opposite sides of the steering block. The first steering cable may extend along a linear path, and the second steering cable may extend along a curved rib of the handle.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of copending U.S. application Ser. No.16/545,685, filed Aug. 20, 2019, which is a continuation of U.S.application Ser. No. 15/097,642, filed Apr. 13, 2016, now U.S. Pat. No.10,441,295, which is a continuation of International Application No.PCT/US2013/065002, filed Oct. 15, 2013, each of which is herebyincorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

This disclosure relates generally to a device useful for creating a voidspace in living tissue such as bone. The device of this disclosureincludes a handle with a control knob for regulating the setting of thedevice. The handle is constructed so that when the device is indifferent positions and positions and orientations relative to thepractitioner using the device, the practitioner is able to easily holdthe handle and set the knob.

BACKGROUND

There are a number of medical devices used to create void spaces such ascavities or channels in living tissue such as bone. One such device is acavity creator. A cavity creator is a surgical tool assembly that, asimplied by its name, forms a cavity in the tissue of a living being. Anumber of cavity creators are specifically designed to form cavities inhard tissue, more specifically, bone. This type of cavity creator may beused in a procedure generally known as a vertebral augmentationprocedure. In a vertebral augmentation procedure, cement is injectedinto a vertebral body that is suffering from fracture so as to stabilizethe vertebral body. It is believed that this stabilization reduces thepain the fracture would otherwise induce in the patient. As part of thisprocedure, to ensure a sufficient quantity of cement is introduced intothe vertebra, it may be necessary to form a cavity, sometimes referredto as a void space, in the vertebra.

A cavity creator that forms a void space in a vertebra typicallyincludes two components, an access cannula and a curette. The accesscannula is a tube like device. The access cannula is inserted in thepatient and into the vertebra to be filled with cement. The curetteincludes an elongated shaft dimensioned to extend through the lumen, thebore, of the access cannula. A tip is located at the distal end of theshaft. A handle is located at the proximal end of the shaft. Once thecurette is seated in the access cannula the tip is positioned to extendradially, outwardly from the longitudinal axis of the access cannula.The rotation of the curette results in the pressing of the tip againstthe bone located outwardly from the access cannula. The pressing of thetip against the bone abrades the bone so as to form a cavity, the voidspace, internal to the vertebra that extends radially beyond the accesscannula. Once this cavity is formed, the curette is withdrawn. Cement orother therapeutic agent is then introduced into the bone and moreparticularly the cavity that surrounds the open distal end of the accesscannula.

Some curettes include a tip that is pivotally attached to the distal endof the curette rod. A drive shaft internal to the rod is selectivelyextended/retracted to pivot the tip between an orientation in which thetip is axially aligned with the shaft and orientation in which the tipis directed away from the shaft. Some of these curettes rely on a thumbwheel and gear assembly mounted to the curette handle to selectivelyextend/retract the drive shaft. Still other of these curettes includeratchet mechanisms again mounted to the handle, to extend/retract thedrive shaft.

A disadvantage of a number of these curettes is that their internalcomponents do not allow one to easily set the extended state position oftheir drive rods. This means that, in turn, it is difficult to set thistype of curettes so as to with a degree of precision, control the extentto which the tip extends beyond the complementary access cannula.Further some of these curettes include numerous parts. As with anydevice, the more parts required to build the device increases the costof providing the device.

Still another known curette includes a shaft with a tip that is formedintegrally with and extends distally from the shaft. At least theconnector that holds the tip to the shaft is formed from a superelasticshape memory material. This curette is initially seated in the accesscannula so that connector and the tip are wholly disposed in thecannula. When the cavity creator is in this state, the connector is bentto generally conform to the shape of the access cannula. The shaft ofthe curette is extended to cause the tip and connector to extend forwardfrom the access cannula. As the connector emerges from the constrainingspace of the access cannula, the potential energy of the connector isreleased. This causes the connector to return to its unconstrained,bent, state. By extension, this results in the movement of the tipradially away from the access cannula. Once the tip is in the desiredposition, the curette is rotated so as to press the tip against theadjacent bone.

The above-described curette includes a control knob for selectivelyextending/retracting the shaft. This knob, when rotated, moves towardsand away from the curette. The practitioner then has to adjust his/herhand position relative to the handle in order to set the position of thetip. Having to take this extra step adds to the ergonomic complexity ofusing this type of curette.

Moreover, as a consequence of the rotation of the knob to extend theabove-described curette, the overall proximal-to-distal length of thisdevice increases. Often a fluoroscope is in close proximity to thecavity creator when this procedure is performed. The fluoroscopeprovides real time images of the bone in which the void space is beingformed. The increasing length of the handle of this curette can make itdifficult to position the curette around the fluoroscope.

Further, many curettes, regardless of the type of assemblies that pivottheir tips, share a common problem. When the cavity creator with whichone of these curettes is integral is in certain positions, it isdifficult for the practitioner to hold the handle so as to rotate thehandle and/or set the extent to which the curette shaft is extended. Forexample, there are times when the practitioner forms a void space thatis centered on an axis that extends into the patient through a portallocated on the side of the patient opposite the side of the patientagainst which the practitioner is standing. This is known as thecontra-lateral side of the patient. Thus, if the practitioner isstanding adjacent the left side of the patient, it may be desirable tocreate a cavity that is located in bone best accessed from the rightside of the patient. The presence of equipment, for example afluoroscope, may make it difficult for the practitioner to simplyreposition himself/herself adjacent the right side of the patient. Inthis situation, to form the cavity, the practitioner has to reach acrossthe spine of the patient in order to insert the access cannula. When thecurette is inserted into the access cannula, the handle does not simplyface away from the practitioner as the handle would if located betweenthe practitioner and the patient. Instead, the handle of the curette canbe both spaced away from the practitioner and be directed towards thepractitioner. To set the extended state position of the curette shaft orrod, the practitioner has to reach across the patient. This puts thehand of the practitioner in an awkward position relative to thecomponent of the curette he/she needs to manipulate. This makes itdifficult for the practitioner to set the curette to ensure that tip isproperly positioned.

Furthermore, it should be understood that the creation of a void spaceinvolves more than simply extending and retracting the shaft integralwith the curette. It is also necessary to rotate the curette to pressthe tip against the tissue to be removed. This means that thepractitioner may be required to place his/her hands and fingers in anunusual position in order to both set the extension of the curette androtate the curette.

Still another class of device used to form a void space in bone arechannel creators. A channel creator is typically used to form anelongated bore, a channel, in the bone to which the channel creator isapplied. These channels are typically smaller in cross sectional widthand often longer in length than the cavities created by a cavitycreator. The control members associated with a number of these deviceshave share a disadvantage with the cavity creators. It can be difficultto control the device depending on the orientation and position of thedevice relative to the practitioner.

SUMMARY

This disclosure relates to a new and useful medical/surgical device. Themedical/surgical device of this disclosure includes a handle designed tobe held by the practitioner in a single hand. An elongated memberextends forward from the handle. A working tip is located at the distalend of the elongated member. Internal to the handle is a mechanism forregulating the actuation of the working tip. A knob is rotatably mountedto the handle so the practitioner can regulate the actuation of theworking tip. The knob is rotatably mounted to the handle so thatregardless of the orientation and position of the handle relative to thepractitioner using the device, the practitioner can, with the thumb orfingers of the hand holding the handle set the knob.

In many versions of this disclosure the handle and knob are collectivelydimensioned so that the knob is mounted to the handle so as to extendoutwardly from opposed side surfaces of the handle and from a surfacethat bridges the side surfaces. This bridge surface may be the topsurface, the front surface the bottom surface or the rear surface of thehandle.

One version of this disclosure is a new and useful cavity creator forcreating cavity in the tissue, such as bone, of a living being. Thecavity creator of this disclosure includes an access cannula and acurette. The curette is constructed so that, through a wide range oforientations and positions of the cavity creator relative to thepractitioner, the practitioner with minimal concentration and effort canmanipulate the curette to set both the extent to which the tip extendsfrom the access cannula and the orientation of the tip.

The curette of this disclosure includes a handle dimensioned and shapedto be held in between the thumb and fingers of a single hand. A shaftextends forward from the handle. At the distal end, the shaft includesan elbow formed from a superelastic shape memory material. A tip islocated at the free end of the elbow. A drive head is affixed to theproximal end of the shaft. The drive head is disposed in the handle soas to be able to move from essentially the proximal end of the handle toessentially the distal end of the handle.

A knob is rotatably mounted to the handle. While the knob rotates, thelongitudinal position of the knob relative to the handle is fixed. Thehandle and knob are collectively dimensioned so that the knob protrudesaway from a top surface of the handle and adjacent sections of theopposed side surfaces. The knob is engaged with the drive head so thatthe rotation of the knob results in the extension or retraction of thedrive head. The extension or retraction of the drive head results in thelike movement of the curette shaft and attached components.

The above features of the curette of the void creator of this disclosuremake it relatively easy to, with a single hand and throughout a widerange of curette orientations relative to the practitioner holding thecurette, both rotate the handle and rotate the knob. This makes itrelatively easy to, when the cavity creator is in differentorientations, both set the extent to which the tip is extended from theaccess cannula and the orientation of the tip relative to an axisthrough the access cannula.

Another cavity creator of this disclosure includes an alternativecurette. This curette includes an elbow that, while flexible, is notbent to a specific curvature. Steering cables extend proximally from thehandle through the shaft and elbow to the tip. A mechanism internal tothe handle selectively tensions and slacks the steering cables. The knobis the component the practitioner actuates so as to control thetensioning and slacking of the steering cables. The selective tensioningand slacking of the steering cables it is understood regulates theextent to which the elbow flexes the tip away the from the longitudinalaxis of the shaft.

Another version of this disclosure is a channel creator. A prebentflexible elbow extends forward from the handle of this versions of thedisclosure. A tip extends forward from the distal end of the elbow. Thetip is formed from material that, when pushed forward, creates a channelin the tissue. A cable extends proximally from the tip, through theelbow and shaft into the handle. The knob is part of a drive assemblycapable of selectively extending and retracting the cable. When thecable is in the retracted state, the cable places a tension on theelbow. The tension holds the elbow so that the elbow and tip aresubstantially in line with the longitudinal axis of the shaft. When thecable is in the extended state, the tension on the cable is reduced.Owing to the shape memory characteristics of the elbow, this allows theelbow to return the curved shape. When the elbow is so curved, thelongitudinal axis of the tip is angled relative to the longitudinal axisof the shaft.

The handle, knob and control mechanism assembly of this disclosure mayhave other applications than setting the angular position of a voidcreating tip relative to the longitudinal axis of the shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure is pointed out with particularity in the claims. Theabove and further features and advantages of this disclosure areunderstood from the following Detailed Description taken in conjunctionwith the accompanying drawings in which:

FIG. 1 is an exploded view of the components forming a cavity creator ofthis disclosure;

FIG. 2 is an exploded view of the components forming the curette of thecavity creator of this disclosure;

FIG. 3 is a view of the left side of the handle of the curette;

FIG. 4 is a view of the right side of the curette;

FIG. 5 is a plan view of the proximally directed surface, the back, ofthe handle;

FIG. 6 is a plan view of the distally directed surface, the front of thehandle;

FIG. 7 is a plan view of the top of the handle of the handle;

FIG. 8 is a plan view of the bottom of the handle and knob;

FIG. 9 is a perspective view of the handle and knob of the curette;

FIG. 10 is a plan view of the interior of one of the left side shell ofthe handle of the curette;

FIG. 11 is an exploded view of the curette shaft and the componentsconnected to the shaft;

FIG. 12 is a cross sectional view of the knob of the curette;

FIG. 13 is a perspective view of the knob;

FIG. 14 is a cross sectional view of the interior of the handle and thecomponents internal to the handle of the curette;

FIG. 15 is a cross sectional view of the distal end of the cavitycreator when the tip of the curette is in the retracted state;

FIG. 16 is a side view when the tip of the curette is in the extendedstate.

FIG. 17 is a cross sectional view of an alternative curette of thisdisclosure;

FIG. 18 is a enlarged cross sectional view of the shaft of the curetteof FIG. 17;

FIG. 19 is a side plan view of a channel creator of this disclosure;

FIG. 20 is a cross-sectional view of the channel creator of FIG. 19;

FIG. 21 is a exploded view of the creator of FIG. 19; and

FIG. 22 is a perspective view of an electrosurgical tool constructed inaccordance with this disclosure.

DETAILED DESCRIPTION I. Cavity Creator with First Curette

FIG. 1 depicts the components forming a cavity creator 30 of thisdisclosure. Specifically, cavity creator 30 includes an access cannula34 and a curette 48. The access cannula 34 includes a tube 36 formedfrom material able to penetrate both soft tissue and hard tissue (bone).The distal end of tube 36 may have beveled edge to facilitate theinsertion of the tube into the patient. (Here, “distal” is understood tomean away from the practitioner holding the cavity creator 30, towardsthe site to which the cavity creator is applied. “Proximal” isunderstood to mean towards the practitioner and away from the site towhich the cavity creator 30 is applied.) A handle 38 is molded orotherwise secured over the proximal end of tube 36. The handle 38 isformed with a fitting 40 that opens into the lumen internal to tube 36.While not identified, the fitting is formed with threading. Thethreading facilitates the releasably coupling of either a cannula filledwith cement or a syringe like device filled with cement to the accesscannula.

Curette 48 includes a handle 50. A shaft 160 is moveably attached to thehandle so as to be extended, move distally, and retracted, moveproximally. At the distal end of the shaft 160 an elbow 164 is present.Elbow 164 is able to flex and return to its original bent shape. A tip168 is located at the end of the elbow distal to the shaft. Shaft 160,including elbow 164 and tip 168, are moveably seated in the lumen ofaccess cannula tube 36. By adjusting the extension/retraction of thecurette shaft 160 the extent to which the tip 164 extends radiallyoutwardly access cannula tube 36 is selectively set.

The curette handle 50, as seen in FIG. 2, includes a left shell 52 and aright shell 54. Shells 52 and 54, when assembled together form the bodyof handle 50. More particularly, the shells, as seen in FIGS. 3-10, forma base 56 and a stem 58 that projects distally forward from the base.Generally, the shells 52 and 54 are formed so that handle base 56 can beheld between the thumb and fingers of a single hand. In some versions ofthe disclosure handle 50 is formed so that top to bottom, the base has amaximum length of between 6 and 13 cm. The top surface 57, the proximalfacing surface 61, the bottom directed surface 63 and distal facingsurface 65 of the base 56 are rounded. Base 56 has its widest width inthe plane where the distance across the base immediately below the topsurface 57 is at its widest. This width is between 1.5 and 5 cm. Belowthis plane, the side surfaces 55 of the base 56 taper inwardly towardeach other. The proximal to distal length of the base is greatest in theplane from which the opposed ends of the arch that forms the curved topsurface extends. This length is between 2.5 and 6 cm. Further it shouldbe understood that top surface 57, proximal facing surface 61, bottomdirected surface 63 and distal facing surface 65 of the handle shouldgenerally be considered bridge surfaces in that each of these surfaces,extends between, bridges, the opposed side surfaces 55.

Stem 58 extends forward from the base 56 around an axis that is locatedin or near the plane from which the opposed ends of the top surfacecurve upwardly and inwardly towards each other. The stem has neck 70.The neck has essentially parallel top and bottom surface 82 and 86.Curved side surfaces 84 extend between the opposed ends of the top andbottom surfaces. Top and bottom surfaces are spaced apart a distancethat allows adjacent fingers to be placed across the surfaces 82 and 86with no discomfort. Thus, surfaces 82 and 86 are at a maximum, spaced nomore than 1.5 cm apart from each other.

Forward of neck 70 stem 58 is formed to have a head 96. Head 96 isgenerally circular in shape. Handle 50 is formed so that the head 96extends radially outwardly beyond the surfaces 82, 84 and 86 of stem 58.Shells 52 and 54 are further formed to define in front, distal panel ofthe head a semi-circular cut out 98 (identified in FIG. 2). When thehandle is assembled cutouts 98 go into registration so as to define adistal end opening in the front of stem head 96, opening not identified.

Each shell 52 and 54 is formed with a notch 118. Notches 118 extenddownwardly from the top surfaces of shells 52 and 54. In the depictedversion of the disclosure the proximal end of each notch 118 is definedby a web 112 internal to the shell that extends longitudinally top tobottom through the shell. The web 112 of left side shell 52 seen in FIG.10. Each web 112 is further formed to have semi-circular cutout 114, oneidentified in FIG. 2, that opens into the notch. The distal end of eachnotch 118 is defined by a web 120 that, like web 120 extends inwardlyfrom the outer portion of the shell 52 or 54 with which the web isintegral. Web 120 is parallel to and spaced distally forward of web 112.Each web 120 is formed with a semicircular cutout 122, one identified inFIG. 2. Cutouts 114 and 122 are understood to be centered on the axisaround which handle stem 58 is centered.

Internal to the shells 52 and 54 are additional webs that extendinwardly from the inner surfaces of the side panels of the shells. Twowebs, webs 126 and 128, extend laterally, proximally to distally throughthe shell 52 or 54 with which the web is integral. The topmost of thesewebs, web 126 is the structural component of the shell against whichwebs 102 and 120 terminate. A web 130 that is parallel with andproximally spaced away from web 112 also extends upwardly from web 126.

Each shell 52 and 54 has two additional pairs of proximally-to-distallyextending parallel webs. A first pair of webs, webs 134 and 136 extendsforward from the inner surface of the rim of the shell that forms theproximal end of the shell. Webs 134 and 136 abut web 102. Web 134 islocated above web 136. Webs 134 and 136 are equidistantly spaced fromthe axial line around which stem 58 is centered. A second pair of webs,webs 138 and 140, extends forward from the distal face of web 120. Webs138 and 140 extend from the base 56 of the body of the handle and intostem head 96. Web 138 is coplanar with web 134. Web 140 is coplanar withweb 136. Within the stem neck 70 each web 138 and 140 has a break, notidentified. Thus while not identified it should be understood that eachweb 138 has a proximal section located primarily in base 50 of the bodyand a distal section located in the stem head 96.

The left side shell, shell 52 is formed to have three posts 144 thatextend inwardly from the inner face of the side panel of the shell. Eachpost 144 is formed with a closed end bore (not identified). Right sideshell 54 is formed to have three openings 148, identified in FIG. 2.Each opening 148 is formed in a recess 146 located inwardly from theside panel of the shell 54. When shells 52 and 54 are assembled togetherto form the body of handle 50, each right side shell opening 148 is inregistration with one of the posts 144 formed in the left shell 52.Fasteners 152 that extend through the right shell openings 148 into theleft shell posts 144 hold the shells together to form the body of thehandle 50.

Curette shaft 160, now described with reference to FIG. 11, is generallytubular in shape. Shaft 160 is formed of material that, when the shaftis axially loaded resists axial buckling of the shaft. The shaft 160 isalso formed from a biocompatible metal. Shaft 160 has a diameter thatallows the shaft to slide in and out of the opening in the housing stemdefined by cutouts 98.

A drive head 152 is located at the proximal end of shaft 160. In crosssection, in planes perpendicular to the longitudinal axis of shaft 160,the drive head can be considered to be oval in shape. Drive head 152 isdimensioned to move within the space between webs 134 and 136, throughopenings defined by cutouts 114 and 122 and in the space between webs138 and 140. The longitudinally extending opposed curved side surfacesof the drive head 152 are formed with threading 153.

The proximal end of curette shaft 160 is disposed in a bore 154 thatopens in the distally directed face of the drive head 152 and extendsproximally from that face. A set screw 155 holds shaft 160 to drive head152. Set screw 155 is disposed in a threaded longitudinally extendingbore 156 that extends from bore 154 to a side surface of the drive head.Screw 155 seats in an indentation 161 formed in shaft 160. Forward ofdrive head 152 indicia 163 (seen in FIGS. 2 and 11) are formed on shaft160. The depicted indicia 163 are circular rings.

Elbow 164 is formed from a shape memory material, sometimes called asuperelastic material. This is a material that, once subjected to aforce will deform and, upon release of the force, will return to theoriginal shape. One biocompatible superelastic material from which elbow164 is formed is a nickel titanium alloy known as Nitinol. In someversions of the disclosure, shaft 160, elbow 164 and tip 168 are formedout of a single piece of Nitinol. The curette 48 is constructed so thatelbow 164 extends outwardly from the plane that extends perpendicularlyrelative to the top-to-bottom longitudinal axis through handle 50. Theelbow 164 subtends an arc that, extending distally forward from shaft160, curves upwardly away from the shaft. In some versions of thisdisclosure, elbow 164 subtends an arc of between 20 and 50°.

Tip 168 is integral with or attached to the free end, the distal end, ofelbow 164. In the illustrated version of the disclosure, tip 168 isoblate circle. Tip 168 has a diameter that is greater than the width ofthe elbow 164. Here elbow “width” is understood to be the distanceacross the minor axis of the elbow 164. Generally it should beunderstood that shaft 160, elbow 164 and tip are formed so as that theelbow can be flexed sufficiently such that the each of these componentscan fit in and slidably move in the lumen of the access cannula tube 36.

A knob 170, seen best in FIGS. 12 and 13, is rotatably attached to thecurette handle 50 to control the extension/retraction of shaft 160relative to the handle. The knob 170 is formed to have tubular shapedhub 172. Hub 172 defines a bore 174 of sufficient diameter that drivehead can seat in and move within the hub. The hub 172 is further formedso that the distal section of the inner surface of the hub has threading176 that extends into the bore 174. Hub threading 176 is designed toengage threading 153 integral with drive head 152. The outer diameter ofhub 172 is such that the proximal end of the hub can seat in and rotatein the circular opening formed by shell cutouts 114 and the distalportion of the hub can seat in and rotate in the circular opening formedby shell cutouts 122. The overall length of hub 172 is such that whencurette 48 is assembled, the proximal end of the hub is approximatelyflush with the proximal surfaces of webs 112 and the distal portion ofthe hub is located forward of webs 120.

A flange 178, generally in the shape of a washer extends radiallyoutwardly from the outer surface of hub 172. A ring 180 extendscircumferentially around the outer perimeter of flange 178. Ring 180extends proximally and distally relative to the flange 178. The ring hasa proximal to distal length that allows the ring to be seated in thesingle notch in the body of the curette handle 50 formed by notches 118.Ring 180 is formed with indentations 182 that function as finger grips.Webs 184 extend outwardly from the opposed surfaces of flange 178. Eachweb 184 extends between the outer surface of the hub 172 and the innersurface of the ring 180 to provide reinforcing strength to the knob 170.

The components forming curette 48 are dimensioned so that when curette48 is assembled, knob ring 180 projects outwardly from the opposed sidesurfaces 55 and the handle body and the interconnecting top surface 57.More particularly, the ring indentations 182 are located outwardly fromthese body surfaces. In many versions of the disclosure, the portion ofknob that protrudes radially outwardly out at least 1 mm from thesesurfaces of the body subtends an arc of at least 150°. In many versionsof the disclosure the continuous exposed section of the knob extendsthrough an arc of at least 180°. In more preferred versions of thedisclosure the exposed portions of the knob subtend an arc of at least200°. For ease of operation in many versions of the disclosure, curette48 is designed so that the arcuate section of the knob that protrudesradially outwardly from the body of the handle at least 180° extends atleast 2 mm outwardly from the adjacent top and side surfaces of thehandle.

The initial step of using cavity creator 30 of this disclosure is theinsertion of the access cannula 34 into the bone in which the voidspace, the cavity, is to be created. Curette 48 is then fitted to theaccess cannula 34. More particularly, the curette elbow 164 is bent sothe shaft 160, elbow 164 and tip can be fitted into the lumen, the bore,of access cannula tube 34. When the cavity creator 30 is in this state,shaft 160 is in the fully retracted state so tip 168 is in closestposition relative to the handle. When curette 48 is in this state, mostof the body of the drive head 152 is disposed in the spaced internal tothe handle 50 proximal to knob 170, between webs 134 and 136.

Owing to the dimensioning of the components forming cavity creator 30,when the cavity creator is in this state elbow 164 and tip 168 are, asseen in FIG. 15, disposed within the distal section of access cannulatube 36.

The cavity creator process continues with the extension of shaft 160.The practitioner extends the shaft by rotating knob 170. Given that theposition of the knob on handle 50 is fixed, the rotation of the knob istransferred through knob threading 176 and drive head threading 153 tothe drive head 152. The rotation of the knob against the drive headwould be expected to cause the drive head 152 and, by extension, shaft160 to move forward. However, the resistance of the bone adjacent thedistal end of access cannula tube 36 prevents tip 168 from protrudingoutwardly. The ability of tip 168, elbow 164 and shaft 160 to resistaxial loading means that, instead of the tip moving distally, therotation of the knob 170 results in the handle moving proximally. Morespecifically, the handle 50 moves proximally away from access cannulafitting 40. More specifically the distally directed face of stem head 86moves away from fitting 40. This movement results in one or more ofshaft indicia being exposed adjacent the access cannula fitting 40. Thenumber of exposed indicia provides the practitioner with an indicationof the length of the exposed proximal section of shaft 160.

The practitioner then rotates the handle while simultaneously applying adistally directed force. These forces result in the tip 168 beingpressed against the surrounding bone. This pressing of the tip againstthe bone abrades the bone so as to leave a void space that is locatedradially outwardly the distal open end of access cannula tube 36. Thepractitioner presses inwardly on the handle until the distally directedface of handle stem head 96 again presses against the access cannulafitting 40.

Thus at the end of the process a void, a cavity, is formed immediatelyforward the distal end of the access cannula tube 36. This void has adepth, axial distance from tube 36 to the distal end of the void, equalin distance to the distance to which the handle 50 originally wasdisplaced proximally away from the cannula 34. This is why thepractitioner monitors the exposure of the shaft indicia 163, todetermine the extent to which the handle was originally displaced. Aspart of this procedure it should be further understood that the shaftmay be rotated back and forth around an arc of less than 360°. Thisresults in a like rotation of elbow 164 and tip 168. Consequently thevoid space formed by the cavity creator 30 of this disclosure willoccupy an arc of less than 360° around the distal end of the accesscannula tube 36. Thus, using the cavity creator 30 of this disclosure,it is possible to both control the depth of the void space that iscreated as well as the degree to which the void space circumferentiallysurrounds access cannula tube 36.

In an alternative use of the cavity creator of this disclosure, thepractitioner advances the shaft 160 while simultaneously holding curettestem 58 against the access cannula fitting 40. The forward movement ofthe shaft 160 results in the movement of elbow 164 out of the distal endof the access cannula tube 36. The freeing of the elbow 164 from theconstraint of the tube releases the potential energy of the elbow; theelbow flexes towards the formed curved shape of the elbow. This flexingresults in the movement of tip 168 radially away from the longitudinalaxis of the access cannula as seen in FIG. 16.

At this time the tip 168 presses against the surrounding bone. Handle 50is rotates so as to cause a like rotation of the tip 168. Tip 168presses against the bone. This pressing of the tip against the boneabrades the bone so as to leave a void space that is located radiallyoutwardly the distal open end of access cannula tube 36.

Once the void space is created, the practitioner rotates the thumb so asto retract tip 168 back into the access cannula tube 34. Curette 48 isthen withdrawn from the access cannula 32. The practitioner is then ableto perform the next part of the procedure for which the creation of thevoid space was required.

Curette handle 50 of the cavity creator 30 of this disclosure can beheld in a single hand. In some procedures the cavity creator 30 isoriented so the distally directed face of handle stem 58 generally facesaway from the practitioner. When curette 48 has this orientationrelative to the practitioner, it is a simple task to, with fingers, holdthe base 56. When the handle 50 is so grasped, the stem neck easily sitsbetween the forefinger and the middle finger. The practitioner uses thethumb of the hand holding the handle to rotate knob 170.

In some procedures, cavity creator 30 is oriented so that the distallydirected face of handle stem 58 is generally directed towards thepractitioner. When the handle is so oriented, the practitioner caneasily hold the handle from the top such that the fingers are disposedagainst one of the side surfaces 55 and the thumb against the opposedside surface 55. Knob 170 is rotated by the repositioning of the thumbfrom against the side surface 55 to against the knob. Thus, regardlessof the orientation of the cavity creator 30, the practitioner is ableto, with minimal effort, grasp the curette handle 50 and rotate the knob170 so as to both extend/retract the tip and rotate the tip.

It should further be understood that when knob 170 is mounted to thehandle 48 to rotate in a plane that is fixed relative to the handle.This means that as the knob rotates the practitioner does not have toreset the thumb or finger used to rotate the knob in order to compensatefor the shifting position of the knob relative to the handle.

In many versions of this disclosure, the drive head and knob threading153 and 176 are formed so that a complete 360° rotation of the knobresults in the linear displacement of the shaft by a maximum of 1.2 cm.This allows the practitioner to, by only slightly rotating the knob 170,finely control the extent to which the tip 168 extends radially from theaccess cannula tube 36. A related feature is that with a singlemovement, typically of the thumb the practitioner can rotate knob 170 atleast 180°. This is because the knob protrudes from both the top surface57 and side surfaces 55 of the handle. This means with a single movementof the thumb the practitioner can advance shaft 160 a distance of atleast 0.6 cm. Collectively these design features mean that the cavitycreator of this disclosure provides the practitioner with the ability toadvance the tip by both relatively fine distances or, when required, bya relatively long distance in the short time required to engage in fullstroke of the thumb or finger.

Curette 48 of this disclosure essentially only has two moving parts; theshaft and attached components; and knob 170. Thus given that thiscurette has relatively few components, in comparison to curettes withmore moving components, it can be more economical to provide.

II. Alternative Curette for Cavity Creator

FIG. 17 depicts in cross section an alternative curette 210 thatincludes the features of this disclosure. Curette 210 is used withaccess cannula 34 (FIG. 1) to form an alternative cavity creator.

Curette 210 includes a handle 212. Handle 212 has the general outershape and dimensions of handle 50 of curette 48. Internal to the handle212 are webs 214 and 216 that are analogues to webs 134 and 136,respectively. Also internal to the handle are webs 218 and 220. Webs 218and 220 are analogues to webs 138 and 140, respectively. Webs 218 and220 do not extend completely into the stem of handle 212. Internal tothe handle a rib 224 extends inwardly from the bottom of the neck of thestem. Extending distally, the overall height of the rib decreases as therib 224 curves downwardly. Handle 212 is also formed to have a curvedrib 226. Rib 226 is generally C-shaped. On end of rib 226 is locatedabove and adjacent the distal end of web 216. Rib 226 then curvesdownwardly and distally forward. From the lowest position with thehandle rib 226 curves upwardly so as to approximately point to rib 224.

A shaft 260 extends forward the distally directed face of the stem ofhandle 212. A hollow shaft 260 is formed from stainless or Nitinol andis tubular in shape. The proximal end of shaft 260 is seated in a block230 of handle 212. Block 230 is similar to below described block 302 ofFIG. 21. Internal to handle 212 are webs with cutouts similar to cutouts294 also seen in FIG. 21. Owing to the seating of the block 230 in thecutouts, block 230 is inhibited from rotating within the stem of handle212. Shaft 260 is statically mounted to the block 230. Thus shaft 260,like block 230, is static relative to handle 212.

A flexible elbow 262 extends forward from the proximal end of shaft 260.In some versions of the disclosure, shaft 260 and elbow 262 are formedas a single component. Slots 264, one identified, are cut into the elbowto provide the elbow with flexibility. A tip 268 extends forward fromthe distal end of elbow 262. Tip 268 is formed from material and isshaped so that when the tip is rotated and pressed against bone, the tipabrades the bone. Shaft 260, elbow 262 and tip 268 are understood to bedimensioned so that these components can slidably fit within the axiallyextending lumen of access cannula tube 36. A number of cavity creatorsof this version are constructed so that when shaft 260 is fully seatedin the access cannula tube 36, handle 212 abuts the access cannulafitting 40, and the elbow 262 is flexed straight, tip 268 projects atleast 1.5 cm forward of the tube 36. In more preferred versions of thedisclosure when the cavity creator of this disclosure is in this state,the tip 268 extends at least 2.5 cm forward from the access cannula tube36.

Two steering cables 240 and 242 extend forward from handle 212 throughshaft 260 and elbow 262. As seen best in FIG. 18, cables 240 and 242 arelocated on opposed sides of the shaft 260 and, while not seen, opposedsides of the elbow. Also, while not seen the shaft 260 may be formedwith opposed lumens wherein each cable extends through a separate one ofthe lumens. These lumens may be formed in ribs that project inwardlyinto the center bore of the shaft. Further, the shaft may be solid sothat the lumens in which the cables 240 and 242 are disposed are twoparallel bores that extend axially through the shaft. The distal ends ofsteering cables 240 and 242 are attached to opposed sides of theproximal portion of tip 268. Alternatively, the opposed distal ends ofthe steering cables 240 and 242 attached to opposed sides of the distalend of elbow 262.

The proximal ends of the steering cables 240 and 242 are attached to asteering block 230 disposed in handle 212. Steering block 230 has thesame generally oval cross sectional shape of drive head 152. The sidesof the steering block 230 are formed with threading (not illustrated)similar to the threading 153 integral with drive head 152 (FIG. 11).Steering block 230 is formed with a closed end bore 232 that extendsdistally forward from the proximally directed face of the block. Aclosed end bore 234 extends proximally rearward from the distallydirected face of the block 230. Bores 232 and 234 are coaxial.

The proximal end of steering cable 240 is anchored in steering blockbore 232. Cable 240 extends proximally from the steering block over thesurface of rib 226 that faces proximally and downwardly. From rib 226cable 240 extends over rib 224 and into shaft 260. The proximal end ofcable 242 is anchored in steering block bore 234. Cable 242 extendsapproximately along a linear path distally forward from the steeringblock 230 into and through shaft 260.

Curette 210 includes a knob 227 similar to knob 170 (FIGS. 12 and 13). Adifference between the two knobs is that the hub 228 of knob 227 isslightly shorter than the hub 172 of knob 170. Knob 227 is rotatablymounted to handle 212 in the same general manner in which knob 170 ismounted to handle 50. The threading internal to knob hub 228 engages thecomplementary threading on the outer side surfaces of steering block230.

A cavity creator that includes curette 210 is readied for use in thesame general manner in which cavity creator 30 is readied for use. Priorto inserting shaft 260, elbow 262 and tip 268 in the access cannula 34,knob 227 is rotated to place the steering block 230 in the neutralposition. The neutral position is the position in which owing to theposition of the block, steering cables 240 and 242 impose essentiallyidentical forces on the distal end of the elbow 262 or the tip 268. Whenthese forces are essentially identical, the elbow 262 and tip 268 areheld so as to be essentially longitudinally aligned with thelongitudinal axis of shaft 260. When the curette is in this state, theshaft 260, the elbow 262 and tip 268 can be inserted into the accesscannula tube 36.

To create a cavity using this cavity creator, the cannula is pusheddistally forward so as to cause tip 268 to project forward of the accesscannula tube 36. As part of this process knob may be rotated to set theorientation of the elbow 262 and tip 268 relative to the shaft 260. Forexample if there is a desire to direct the tip upwardly as seen in FIG.17, knob is rotated to move steering block 230 proximally. Thismovement, in turn, causes the steering block 230 to pull steering cable242 proximally while simultaneously reducing the tension the blockplaces on steering cable 240. This specific tensioning/slacking of thesteering cables results in cable 242 pulling on the component to whichthe distal end of the cable 242 is attached so that the elbow 262 flexesas seen in FIG. 17.

Alternatively, curette 210 can be set so that elbow 262 and tip 268 aredirected downwardly, opposite the orientation seen in FIG. 17. Thissetting is achieved by rotating the knob 227 so that steering block 230is displaced distally forward. This displacement of the steering blockcauses the block to simultaneously urge steering cable 240 proximallywhile reducing the tension that is placed on cable 242. This results inforces being placed on the component to which the distal ends of thecables are applied that flex the cable downwardly such that the tip 268points towards a location opposite the location to which the tip isdirected in FIG. 17.

Once the tip 268 is oriented in the desired direction, the practitionermay oscillate the tip by rotating the handle 210 through an arc of lessthan 360°. This results in the formation of a void space forward of thedistal end of the access cannula tube 36 that does not extend completelyaround the tube. The rotational position of this void space isunderstood to be set based on the setting of the angular position ofcurette tip 268.

Curette 210 of this version of the disclosure provides the practitionerwith the means to set the angular orientation of the tip 268 relative toshaft 262. This provides a further means to allow the practitioner toselectively form a void space in the bone regardless of the orientationin which the handle is being held. Thus, if the practitioner finds itnecessary to hold the handle 212 upside down, wherein the top surface isdirected towards the patient, by setting the angular orientation of thetip the practitioner can form a void space that is located upwardlyrelative to the portal in the bone through which the cavity creator isinserted in the patient.

Still a further feature of this version of the disclosure is that byselectively adjusting both the extent to which tip 268 is angularlyoffset from shaft 260 and the extent to which the tip is advancedforward from access cannula tube 36, the practitioner can form a voidthat while extending a 1 cm or more form the tube 36 does not projectappreciably radially outwardly from the tube.

III. Channel Creator

A channel creator 280 incorporating the features of this disclosure isnow described with reference to FIGS. 19 and 20. Channel creator 280includes a handle 282 from which a shaft 306 extends distally forward. Apre-bent elbow 310 formed from flexible shape memory material extendsforward from the distal end of shaft 306. A tip 314 extends from thedistal end of elbow 310.

Handle 282 has the same general shape as previously described handles 50and 212. Internal to handle 282 are webs 286, 288, 290 and 292. Webs 286and 288 are substantially identical to previously described webs 134 and136, respectively. Webs 290 and 292 are similar to previously describedwebs 138 and 140, respectively. Webs 290 and 292 are shaped to definerectangular cutouts 294 in the sections of the webs disposed within thehead of the handle stem.

Previously described knob 170 is rotatably mounted to handle 282. Ablock 302 is seated in handle stem. More particularly block 302 isseated in cutouts 294. Webs 290 and 292 and block 302 are collectivelydimensioned so they abut. Webs 290 and 292 thus hold the block 302static in handle 282.

Shaft 306 extends distally forward from the stem of handle 282. Shaft306 is formed from stainless steel or Nitinol and is tubular so as tohave an axially extending lumen, (lumen not identified). The proximalend of shaft 306 is statically mounted in block 302. Not identified isthe bore in the block 302 through which shaft 306 extends. A bent elbow310 is mounted to and extends distally forward from the distal end ofshaft 306. Elbow 310 is formed from a flexible shape memory materialsuch as a nickel titanium alloy. In some versions of the disclosure,elbow 310, when not flexed, subtends an arc of between 45 and 90°.

In the depicted version of the disclosure, elbow 310 is formed so as tohave a cylindrical stem 308. While not identified it can be seen fromFIG. 20 that the stem has a elongated groove that extends along theportion of the elbow that becomes the outer curved surface of the elbow.

A tip 314 extends forward from distal end of elbow 310. Tip 314 isformed from material such as Nitinol. In this version of the disclosure,the tip is shaped so that when the tip is pressed forward, the tip willpenetrate, form a bore or channel in bone or other tissue. In thedepicted version of the disclosure, tip 314 is formed integrally withthe elbow 310. The tip is formed to define a bore 316 that extendsproximally from the distal end of the tip. Bore 316 is a closed endbore. While not seen in the drawings, the tip 314 is formed with alongitudinally extending notch. The notch is contiguous with and extendsproximally from the proximal end of bore 316.

A number of channel creators of this version are constructed so thatwhen shaft 306 is fully seated in the access cannula tube 36, handle 282abuts the access cannula fitting 40 and elbow 310 is flexed straight,tip 314 projects at least 2 cm forward of the tube 36. In more preferredversions of the channel creator of this disclosure when the channelcreator is in this state, the tip 314 extends at least 3 cm forward fromthe access cannula tube 36.

Drive head 152 is slidably disposed in handle 282. More particularly,the drive head is slidably disposed between webs 286 and 290 locatedabove the block and webs 288 and 292 located below the block. Knob 170engages and moves the drive head 152 proximally and distally within thehandle 282 as previously described.

A tensioning cable 298 is attached to and extends distally forward ofthe drive head 152. Cable 298 extends through the lumen of shaft 306. Byextension, the cable 298 extends through block 302. The cable extendsforward of the shaft and through the groove formed in elbow stem 308.Cable 298 then extends around the outer curved surface of elbow 310. Atthe distal end, the cable has a spherical head 299. Cable head 299 isseated in the bore 316 formed in tip 314. The portion of the elongatedbody of the cable 298 immediately proximal to the head 299 is disposedin the section of the notch formed in the tip 314 that extendsproximally away from the bore 316. Cable 298 and tip 314 arecollectively formed so that cable head 299 cannot be pulled through thenotch.

Channel creator 280 is used in combination with access cannula 34 toform a channel in the bone to which the channel creator is applied. Achannel differs from a void space formed by a curette in that a channeltends to be narrower in cross section and longer in length. The accesscannula 34 is initially inserted into the bone in which the channel isto be formed. Knob 170 is then rotated so as to induce the proximalmovement of the drive head 152 and, by extension, cable 298. Therearward movement of the cable causes the cable to straighten out elbow310. The elbow 310 can be straightened, flexed, so that tip 314 isbecomes substantially aligned with the longitudinal axis of shaft 306.Once the elbow is so straightened. Shaft 306, elbow and tip can be slipfitted in the lumen of access cannula tube 36.

Tip 314 is shaped so that by reciprocating the channel creator 280 backand forth the tip forms a channel in the bone to which the tip isapplied. The extent to which the path of the channel extends radiallyaway from the distal end of the access cannula tube 36 is a function ofthe flexure of the elbow 310. The flexure of the elbow is set byrotating knob 170. More specifically, the knob 170 can be rotated toadvance the drive head 152 and by extension, cable 298, forward. Thisresults in the lessening of the extent to which the cable 298 places astraightening tension on the elbow. The lessening of this tension causethe release of the potential energy of the material forming the elbow.This energy returns the elbow to the flexed, bent, shape. By controllingthe extent which the elbow is allowed to return to the flexed shape, thepractitioner regulates the extent to which the channel creator 280, whenadvanced, forms a channel that extends radially from the access cannulatube 36.

Typically, the components forming cavity creator 280 are selected sothat when elbow 310 is fully flexed, fully bent, the distal end of thetip 314 is radially spaced a minimum 1.5 cm from the longitudinal axisof shaft 306. In many versions of the disclosure, the cavity creator 280is constructed so that when the elbow 310 is so flexed, the distal endof the tip 314 is radially spaced at least 2.5 cm from the longitudinalaxis of shaft 306.

The rotational position of the channel relative to the access cannulatube 36 is set by rotating the handle 282. Thus, prior to rotating theknob 170 to set the curvature of the elbow 310 the practitioner mayrotate the handle 282. This rotation establishes the rotation directionin which the tip 316 is directed as the elbow returns to the curvedstate. The illustrated version is designed so that the practitionerknows that the elbow when fully flexed bends away from the bottomsurface of the handle 282.

IV. Alternative Embodiments

The foregoing is directed to specific versions of this disclosure. Forexample, an alternative curette of this disclosure may not have thesingle component shaft-elbow-tip of the disclosed disclosure. In analternative version of the disclosure, the tip may be pivotally attachedto the shaft. In these versions of the disclosure, a drive rod withdrive head is connected to the handle. The handle having the knob ofthis disclosure extends/retracts the drive rod so as to pivot the tiprelative to the handle.

In the described version of the disclosure, the knob is disposed in androtates along an axis that is coaxial with shaft 160. This is not meantto be limiting. In an alternative version of the disclosure, the knob ismounted to the handle so as to rotate around an axis that is orthogonalor otherwise angled relative to the axis of the shaft. Still in someversions of the disclosure, the knob may not rotate about an axis thatintersects or otherwise overlaps the longitudinal axis of the shaft.

Also there is no requirement that in all versions of the disclosure, thebridge surface from which the knob extends be the top surface. Thus insome versions of the handle bridge surface from which the knob extendsmay be one of the distally directed, bottom or proximally facingsurfaces.

Likewise, when the knob is provided, there is no requirement that itinclude the described indentations. In an alternative version of thedisclosure the outer circumferential surface of the knob that is grippedby the thumb or finger may be formed from a material that facilitatesgripping. These materials include textured plastic or rubber.

In some versions of the disclosure, the rotating handle may be replacedby a lever or switch and a ratchet mechanism.

Curette 48 of this disclosure may also be used as a stand alone device.Alternatively, the curette may be incorporated into other assemblies.

While the foregoing description is directed specifically to the cavitycreator of this disclosure, the features of this disclosure are not solimited. The handle 50 and knob 170 assembly of this disclosure may beincorporated into other medical devices where it is desirable to providethe practitioner with one-handed control of both the orientation of thedevice and setting of a moving component that extends from the handle.For example handle 50, drive head 152 and knob 170 may be used toselectively extend/retract the shaft of another medical device. Thesedevices include elongated forceps or scissors used in arthroscopic orendoscopic procedures. The component or components that extend from andthe handle and controlled by the knob may not even be rigid. Forexample, the one or more flexible steering cables may extend from thehandle. These distal ends of these steering cables extend to a flexibledevice such a fluid delivery catheter or an electrode assembly that isinserted in the patient. The selective tensioning of these steeringcables is controlled by the selective rotation of the knob 170. Itshould be appreciated that in these versions of the disclosure, thedrive component/components that are connected to and actuated by therotation of knob will be different from the disclosed drive head. Forexample, if the components controller by the knob are cables, the drivecomponent/components may be one or more spools that are connected to theknob so as to rotate upon rotation of the knob.

Likewise the component regulated by the knob may in some versions of thedisclosure not be a component that performs a mechanical drivefunctions. The knob in some versions of this disclosure may be acomponent that controls the state of an electrical signal. Thus the knobfunction as the component that sets the position of the contact of aswitch or the wiper of a potentiometer. Thus, as depicted in FIG. 22,one construction of this disclosure is one in which attached to thedistal end of a shaft 336 is an electrode 338 (monopolar or bipolar). Inthese versions of the disclosure, the rotation of knob 332, by setting aswitch and/or potentiometer internal to the handle sets the state of thecontrol signal output from the handle 330 over a cable 298 back to acontrol console (not part of the present disclosure and notillustrated). Based on the state of the signal, the control consoleregulates the on/off state of the signal sourced to the electrode and/orthe magnitude of the current or the level of the potential of thesourced current.

Further, this disclosure is not limited to constructions of thedisclosure wherein there is only a single manually actuated controlmember attached to the handle. Thus in a version of the disclosurewherein the device includes a shaft with an electrode tip, the tip maybe selectively positionable through the use of steering cables or atension cable relative to the shaft. In these versions of thedisclosure, the knob be used to set the angular position of theelectrode relative to the shaft. A second control member may be used toregulate the application of a current to the electrode.

In some embodiments of these versions of the disclosure, the secondcontrol member may be a second knob. This second knob may or may not beparallel to the first knob. In still other embodiments of thisdisclosure, the second manually actuated control member may be anothertype of component such as a slide switch or a push button switch.

In the described versions of the disclosure, the shafts that extenddistally from the handle are all shown as being straight. This should beinterpreted as a limiting feature of this disclosure. In some versionsof the disclosure, the shafts, while rigid, may be formed with one ormore curved sections or is formed to have a shape that is continuouslycurved. Likewise, while the shafts of the described versions of thedisclosure may be interpreted to be rigid, this characteristic shouldnot be interpreted as a limiting feature of this disclosure. In someversions of the disclosure, the shafts may be understood to be formedout of material that can be bent. This would allow the practitioner to,at the start of the procedure place custom bends in the shaft tofacilitate the shaping of the device for the specific patient andprocedure. In these versions of the disclosures it would be understoodthat the driven components internal to the shaft would likewise be ableto bend in order to properly function after this shaping.

In still other versions of this disclosure, the distal end of theprebent, flexible elbow may actually be the tip of the device. Forexample, in one version of this embodiment of the disclosure, the devicefunctions as a cement delivery cannula. This type of cannula holdscement for discharge into bone such as a vertebral body. A cementdelivery cannula of this disclosure includes a shaft and a prebent,flexible elbow which have contiguous longitudinally extending throughbores. In these versions of the disclosure, the proximal end of theshaft extends to a fitting that projects proximally from the handle. Thefitting is designed for connection to a unit capable of supplying bonecement to the cannula. For reasons apparent below, this fitting isdesigned to rotate around an axis that extends from the handle. Onecement delivery device to which this cannula can be attached isdisclosed in the Applicant's U.S. Pat. No. 7,658,537, issued 9 Feb.2010, the contents of which are explicitly incorporated herein byreference. The shaft itself is connected to the handle knob similar tohow shaft 160 is connected to knob 170. Thus the knob is rotated toselectively extend or retract the elbow relative to the handle. Thedistal end of the elbow is understood to be open.

The practitioner uses the cement delivery cannula of this disclosure byplacing this cannula in an access cannula similar to access cannula 34.When the cement delivery cannula is placed in the access cannula thecement delivery cannula is initially set so the elbow is in theretracted state. The components of this system are designed so that whenthe elbow is so retracted, the elbow is fully disposed in the accesscannula tube. This typically assumes the access cannula is alreadyfitted in the patient. The unit capable of supplying cement is thenconnected by the handle fitting to the shaft of the cement deliverycannula. The knob is then rotated to set the extent to which the elbowextends forward from the distal end of the access cannula.

Once the position of the cement delivery cannula is so set, the cementdelivery unit is actuated. This typically involves the proximal movementof a plunger. This results in the forcing of cement out of the cementdelivery unit and through the shaft and elbow of the cement deliverycannula and out of this elbow.

Thus this version of this disclosure makes it possible for apractitioner to establish the location forward of the cement deliverycannula from which the cement will be discharged. This location settingin addition to being a radial distance is also a rotational setting. Thepractitioner establishes this setting by rotating the handle. Thishandle rotation it is understood results in a like rotation of shaft andelbow of the cement delivery cannula around the longitudinal axis of theaccess cannula.

Accordingly, it is an object of the appended claims to cover all suchvariations and modifications that come within the true spirit scope ofthis disclosure.

1. A device for creating a cavity or a channel in bone, the device comprising: a handle; a shaft coupled to the handle and comprising a proximal portion seated within the handle, a tip located forward of the handle, and a flexible elbow between the proximal portion and the tip; a first steering cable coupled to the flexible elbow or the tip of the shaft; a second steering cable coupled to the flexible elbow or the tip of the shaft; and a control assembly comprising a knob that is rotatably coupled to the handle and operably coupled to the first steering cable and the second steering cable, wherein the knob is configured to be rotated to tension one of the first steering cable and the second steering cable and slacken the other one of the first steering cable and the second steering cable so as to flex the flexible elbow.
 2. The device of claim 1, wherein the control assembly comprises a steering block axially movable within the handle, wherein the knob is threadably coupled to the steering block, and wherein the first steering cable and the second steering cable are anchored to the steering block.
 3. The device of claim 2, wherein the steering block defines a distal closed end bore and a proximal closed end bore, wherein an end of the first steering cable is anchored to the steering block in the distal closed end bore and an end of the second steering cable is anchored to the steering block in the proximal closed end bore.
 4. The device of claim 1, wherein the handle comprises a curved rib, wherein the second steering cable extends along the curved rib.
 5. The device of claim 4, wherein the curved rib is C-shaped.
 6. The device of claim 1, wherein the handle comprises a base portion and a stem extending distally from the base portion, wherein the knob is rotatably coupled to the base portion and the shaft extends from the stem.
 7. The device of claim 6, where the stem comprises a neck comprising opposing surfaces spaced apart by a distance to accommodate adjacent fingers from a user, and a head extending radially outwardly from the neck.
 8. The device of claim 6, further comprising a mounting block seated within the stem, wherein the proximal portion of the shaft is mounted to the mounting block.
 9. The device of claim 1, wherein the knob is rotatable in a plane perpendicular to an axis of the proximal portion of the shaft.
 10. A device for creating a cavity or a channel in bone, the device comprising: a handle; a shaft coupled to the handle and comprising a proximal portion seated within the handle, a tip located forward of the handle, and a flexible elbow between the proximal portion and the tip; a first steering cable coupled to the flexible elbow or the tip of the shaft; a second steering cable coupled to the flexible elbow or the tip of the shaft; and a control assembly comprising a steering block axially movable within the handle, wherein the first steering cable and the second steering cable are anchored to opposing sides of the steering block so as to provide for simultaneous tensioning of one of the first steering cable and the second steering cable and slackening of the other one of the first steering cable and the second steering cable with axial movement of the steering block.
 11. The device of claim 10, wherein the steering block defines a distal closed end bore and a proximal closed end bore, wherein an end of the first steering cable is anchored to the steering block in the distal closed end bore and an end of the second steering cable is anchored to the steering block in the proximal closed end bore.
 12. The device of claim 11, wherein the end of the first steering cable and the end of the second steering cable are coaxially arranged.
 13. The device of claim 10, wherein the control assembly further comprises a knob threadably coupled to the steering block and configured to be rotated by a user to axially move the steering block within the handle.
 14. The device of claim 10, wherein the handle comprises cutouts, and wherein steering block is rotatably fixed within the cutouts.
 15. The device of claim 10, wherein the handle comprises a curved rib, wherein the second steering cable extends along the curved rib.
 16. The device of claim 15, wherein the curved rib is C-shaped.
 17. A device for creating a cavity or a channel in bone, the device comprising: a handle comprising opposing shells defining an interior of the handle, and a curved rib disposed within the interior; a shaft coupled to the handle and comprising a proximal portion seated within the handle, a tip located forward of the handle, and a flexible elbow between the proximal portion and the tip; a first steering cable coupled to the flexible elbow or the tip of the shaft; a second steering cable coupled to the flexible elbow or the tip of the shaft; and a control assembly operably coupled to the first steering cable and the second steering cable, wherein the second steering cable extends along a surface of the curved rib to orient an end of the second steering cable to be coupled to the control assembly to provide for simultaneous tensioning and slackening of the first steering cable and the second steering cable.
 18. The device of claim 17, wherein the curved rib is C-shaped.
 19. The device of claim 17, wherein the surface faces proximally and downwardly.
 20. The device of claim 17, wherein the first steering cable extends along a linear path. 